clk: rockchip: export clock pclk_efuse_256 for RK3368 SoCs

This exports the clock for the pclk gate of the eFuse that is part of
the RK3368 SoCs. So we can use it from the dt-bindings.

Signed-off-by: Romain Perier <romain.perier@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>